Sampling system

Abstract

An improved sampling system is provided for on-line monitoring of a liquid such as a process liquor in a paper mill or the like. The sampling system includes, in general terms, an improved sampling probe for circulating process liquor from a process tank or the like to a sensor device such as a refractometer for monitoring of selected parameters. The sampling probe includes intake and return conduits having ends nested within an open-ended probe housing disposed within the process tank, such that the intake and return conduit ends are shielded from direct contact with large particulate settling within the tank. The intake and return conduit ends are further arranged for intersection of liquor flow streams associated therewith at a position inset within the probe housing to generate turbulence which tends to sweep large particulate away from the probe while maintaining smaller particulate in suspension to avoid probe clogging. In addition, the sensor device includes a brush unit for preventing accumulation of particulate which could otherwise interfere with the monitoring process.

What is claimed is: 
     
       1. A sampling system for monitoring at least one parameter of a process liquor or the like, said sampling system comprising: a sampling probe having a probe housing extending into the process liquor and defining an open housing end to permit flow of the process liquor into said probe housing, and an intake conduit and a return conduit having open ends disposed within said probe housing for angular intersection of process liquor streams associated with said intake and return conduits at a position slightly inset from the open end of said probe housing;   a sensor unit including a flow block for flow through passage of the process liquor and means for monitoring at least one parameter of the process liquor within said flow block; and   means for circulating the process liquor to said flow block through said intake conduit and for returning the process liquor to said probe through said return conduit.   
     
     
       2. The sampling system of claim 1 wherein said intake and return conduits are interconnected for intersection of process liquor streams associated therewith. 
     
     
       3. The sampling system of claim 1 wherein said circulating means comprises a pump. 
     
     
       4. The sampling system of claim 1 wherein said monitoring means comprises an optical detector, and further wherein said flow block defines a sight window to permit viewing of the process liquor within said flow block by said optical detector. 
     
     
       5. The sampling system of claim 4 wherein said optical detector comprises a refractometer. 
     
     
       6. The sampling system of claim 1 further including cleaning means within said flow block for cleaning particulate material from said sensor unit. 
     
     
       7. A sampling system for monitoring at least one parameter of a process fluid or the like, said sampling system comprising: a sampling probe having a probe housing extending into the process fluid and defining an open housing end to permit flow of the process fluid into said probe housing, and an intake conduit and a return conduit having ends disposed within said probe housing at a position at least slightly inset from the open end of said probe housing;   a sensor unit including a flow block for flow through passage of the process fluid and means for monitoring at least one parameter of the process fluid within said flow block;   means for circulating the process fluid to said flow block through said intake conduit and for returning the process fluid to said probe through said return conduit,   said circulating means comprising a pump and further including a pair of supply conduits coupled to said flow block of said sensor unit, and means for connecting said supply conduits respectively to said intake and return conduits, said connecting means including reverse flow means for periodically reversing the connection of said supply conduits to said intake and return conduits for reversing the direction of process fluid flow through said supply conduits and said flow block.   
     
     
       8. A sampling system for monitoring at least one parameter of a process fluid or the like, said sampling system comprising: a sampling probe having a probe housing extending into the process fluid and defining an open housing end to permit flow of the process fluid into said probe housing, and an intake conduit and a return conduit having ends disposed within said probe housing at a position at least slightly inset from the open end of said probe housing;   a sensor unit including a flow block for flow through passage of the process fluid and means for monitoring at least one parameter of the process fluid within said flow block; and   means for circulating the process fluid to said flow block through said intake conduit and for returning the process fluid to said probe through said return conduit; and   cleaning means within said flow block for cleaning particulate material from said sensor unit, said cleaning means comprising a brush, and further including drive means for moving said brush to clean said sensor unit.   
     
     
       9. The sampling system of claim 8 wherein said drive means comprises a drive motor having a drive shaft, a driven shaft carrying said brush, hermetically sealed coupling means interconnecting said drive and driven shafts, and flush means for flushing particulate from said coupling means into said flow block. 
     
     
       10. The sampling system of claim 9 wherein said flush means comprises a water flush supply, a valve for opening said water flush supply to flow past said driven shaft into said flow block, and timer means for intermittently opening said valve. 
     
     
       11. The sampling system of claim 9 wherein said sealed coupling means comprises a magnetic coupling. 
     
     
       12. A sampling system for monitoring at least one parameter of a process fluid or the like, said sampling system comprising; a sampling probe having a probe housing extending into the process fluid and defining an open housing end to permit flow of the process fluid into said probe housing, and an intake conduit and a return conduit having ends disposed within said probe housing at a position at least slightly inset from the open end of said probe housing, said intake and return conduits being mounted within said probe housing for intersection of process fluid streams associated with said intake and return conduits at a position at least slightly inset within said probe housing;   a sensor unit including a flow block for flow through passage of the process fluid and means for monitoring at least one parameter of the process fluid within said flow block;   means for circulating the process fluid to said flow block through said intake conduit and for returning the process fluid to said probe through said return conduit; and   cleaning means for cleaning particulate material from said sensor, said cleaning means comprising a brush, a drive motor having a drive shaft, a driven shaft carrying said brush, hermetically sealed coupling means interconnecting said drive and driven shafts, and flush means for flushing particulate from said coupling means into said flow block.   
     
     
       13. The sampling system of claim 12 wherein said flush means comprises a water flush supply, a valve for opening said water flush supply to flow past said driven shaft into said flow block, and timer means for intermittently opening said valve. 
     
     
       14. The sampling system of claim 12 wherein said sealed coupling means comprises a magnetic coupling. 
     
     
       15. The sampling system of claim 12 wherein said intake and return conduits are interconnected for intersection of process fluid streams associated therewith. 
     
     
       16. The sampling system of claim 12 wherein said circulating means comprises a pump. 
     
     
       17. The sampling system of claim 12 wherein said probe housing is oriented to substantially prevent entry thereinto of particulate material settling within the process fluid. 
     
     
       18. A sampling system for monitoring at least one parameter of a process fluid or the like, said sampling system comprising; a sampling probe having a probe housing extending into the process fluid and defining an open housing end to permit flow of the process fluid into said probe housing, and an intake conduit and a return conduit having ends disposed within said probe housing at a position at least slightly inset from the open end of said probe housing, said intake and return conduits being mounted within said probe housing for intersection of process fluid streams associated with said intake and return conduits at a position at least slightly inset within said probe housing.   a sensor unit including a flow block for flow through passage of the process fluid and means for monitoring at least one parameter of the process fluid within said flow block;   means for circulating the process fluid to said flow block through said intake conduit and for returning the process fluid to said probe through said return conduit; and   cleaning means for cleaning particulate material from said sensor;   said circulating means comprising a pump and further including a pair of supply conduits coupled to said flow block of said sensor unit, and means for connecting said supply conduits respectively to said intake and return conduits, said connecting means including reverse flow means for periodically reversing the connection of said supply conduits to said intake and return conduits for reversing the direction of process fluid flow through said supply conduits and said flow block.   
     
     
       19. A sampling probe for drawing and returning a sample of process liquor or the like for analysis, said sampling probe comprising; a probe housing extending into the process liquor and having an open end oriented to substantially prevent entry thereinto of particulate material settling within the process liquor;   an intake conduit and a return conduit mounted within said probe housing and having adjacent ends disposed at a position slightly inset from said probe housing open end and oriented for substantial angular intersection of process liquor streams associated with said intake and return conduits.   
     
     
       20. A sensor unit for monitoring at least one parameter of a process fluid or the like, said sensor unit comprising; a flow block for flow through passage of at least a portion of the process fluid to be monitored;   a sensor head including a sensor device for monitoring the process fluid within said flow block, said sensor device comprising a refractometer, and a sight window formed on said flow block; and   means for cleaning particulate material from said sensor device, said cleaning means comprising a brush within said flow block.   
     
     
       21. The sensor unit of claim 20 wherein said cleaning means further includes a driven shaft carrying said brush, hermetically sealed coupling means interconnecting said drive and driven shafts, and flush means for flushing particulate from said coupling means into said flow block. 
     
     
       22. The sensor unit of claim 21 wherein said flush means comprises a water flush supply, a valve for opening said water flush supply to flow past said driven shaft into said flow block, and timer means for intermittently opening said valve. 
     
     
       23. The sensor unit of claim 22 wherein said sealed coupling means comprises a magnetic coupling. 
     
     
       24. The sensor unit of claim 20 further including means for automatically and intermittently operating said cleaning means.